Press button control for elevators and the like



Patented a. 1, 1935 PATENT OFFICE PRESS BUTTON CONTRL FOR ELEVATORS AND THE LIKE Theodor Hoflmann, Berlin-Reinickendorf, Germany Application February 23, 1933, Serial No. 658,027 In Germany February 25, 1932 6 Claim.

This invention relates to a press button control for elevators and the like, in which only one control circuit is employed, parallel to which different resistances are arranged which are individually actuated by means of press buttons. In this connection a bridge arrangement of resistances and a switching mechanism are employed which will be hereinafter described in detail. In this manner the arrangement is rendered insensitive to the voltage variations in the supply main as the operation of the resistance bridge arrangement is not influenced by voltage variaping place.

tions.

An embodiment of the invention is illustrated byway of example in the accompanying drawing in which:-

Fig. l is a diagrammatic view showing the entire principle of the resistance bridge. 4

Fig. 2 shows .an elevator control in which this principle is utilized.

The arrangement and operation of the con trol will be hereinafter described.

If voltage is applied across a resistance l-2, no current will flow through the wire 4-6 if the resistances 3-4 and 4-5 are equal (see Fig. 1). Resistance l-6 is made equal to resistance 6-2. If for example the resistance 4-5 is varied, current will flow through the wire 4-6 until the resistance 3-4 becomes equal to the resistance 4-5. If a motor 4|, relay or the like is connected up in the wire 4-6 and if a device 42, which for example changes the resistance branch 3-4, is actuated by the motor or relay, this device, if the resistance branch 4-5 has been intentionally changed by the device 43, will continue to operate until the resistance 34 is equal to the resistance 4-5 because at this instant no current flows through the wire 4-6 and a relay or motor connected up therein wouldbecome currentless. Thus by merely changing the resistance 4-5 it is possible to produce anarrangement which accurately follows these alterations and at the same time controls for example stopping places of an elevator.

In Fig. 2 a bridge resistance 'l-3 is connected up to the supply mainr 9-H! is'a resistance in the cage .II which is varied by press buttons I2 corresponding in number to the number of stop+ ping places. A certain resistance corresponds to each press button and therefore to each stopl3-l4 is the other bridge branch. This bridge branch is similarly constructed to the resistance branchfl-Ill. The resistancein the resistance branch l3-l4 is changed by one of a plurality of contact strips l5 separated from one another each corresponding to a different floor and cooperating with a contact arm l6. The contact arm I6 is actuated for example by the motor I1 and thus alters the resistance I3-l4.

The motor I! is connected to the points l8-I9 5.

of the bridge. These points correspond to the points 4-6 in Fig. 1. If by actuatin'ga press button l2 a certain part of resistance 9-"! is switched in, the motor l'l, if the same resistance is not switched in the resistance branch I3-l4, will run until the contact arm I6 and contact strip l5 have made theresistance l3-I4 equal to the resistance B-IO. ,At this instant there exists no voltage between the points l6 and I9, so that the motor 11 stops. A further arm 20 15 cooperating with a plurality of contact strips 2| separated from one another and each corresponding to a different floor is rigidly connected to the contact arm l6. The individual stopping places are controlled by this second contact arrangement 20-2! which runs in synchronism with the contact arrangement l5-l6. Wires, corresponding in number to the number of stopping places, extend from the contact bar 2| to the floor switches 22 which cooperate with .a cam carrier 34 in the elevator shaft and are actuated from the cage or'are actuated in accordance with the position of the elevator at the respective floors by apparatus in the engine room driven by the elevator winch 35. Two leads corresponding to the upward and downward travel of the cage extend from the floor switches to the reversing relays 23 of the elevator motor 24.

The attraction'of a relay 25 is retarded by the damper 26, the operation of which is illustrated by way of example in the drawing, so that the contact 21 is only closed after a certain time has elapsed. 28 is an auxiliary relay which serves on the one hand for applying the voltage of the, supply mains 30, 30a, 30b across the bridge resistance 'I-8 by means of the contact 29, and on the other hand, for actuating the relay. The switching operation when controlling a certain stopping place takes place as follows.

Assuming that the cage is et the fourth floor, tliat is in its highest position so that the uppermost floor switch 34 is switched out by the cam carrier 34 which is fixed on the cage II by theconnection 68 and for example a press button l2 in the cage is actuated which corresponds to the second floor so that the resistance 33-!!! in the cage II is switched in, the current will then flow along the iollowing path:

The current flows from the supply mains phase 30b through the wire 46 to the relay 28,

Oct. 1, 1935. 'r. HOFFMANN 2,015,799

PRESS BUTTON CONTROL. FQR ELEVATORS AND THE LIKE med Feb. 23, 1955 

